With its 2-m-thick walls and squalid cells, the Patarei sea fortress on the edge of Tallinn, capital of the Baltic republic of Estonia, has long borne witness to the brutality of occupation. Built in 1840 by Russian Czar Nicholas I, it was used[an error occurred while processing this directive] as a prison and execution site by the two powers that marched into Estonia in the 20th century, Nazi Germany and the Soviet Union. But Estonia is once again an independent country, the last prisoners have gone, and one Friday night last month, the fortress was literally pulsating with a new kind of energy as hundreds...